1961 Johnson Seahorse 10hp - slips gear when in full throttle.

[On The Lake]

Hi, I'm new to this forum and this is my first post.

I just acquired a 10hp 1961 Johnson Seahorse in (what I thought was in) good shape. Serial No. 318197, Model QD – 22F.

Overall, it starts easily and appears to be in good running order. Very clean inside the cowl. When putting the motor in forward gear, at slow speeds all is ok. Upon throttling up to full speed, I think the gear is slipping as the engine revs higher, but speed slows down. The forward/reverse lever is still in the forward position but the engine seems to rev higher without accompanying increase in speed.

Any thoughts from experienced motor owners?

[boats.net]

Check hub in prop, if has a rubber hub it may be slipping or has a sheared prop pin. Check lower unit oil for metal shavings in oil or water in oil, signs of lower unit internal damage.

[On The Lake]

That was exactly the problem. The rubber bushing was likely aged and not gripping the prop housing tight enough. New 8.25” prop and problem solved. Thank you so much!